Kinetics of the thermal decomposition of some transition metal sulfates

Tagawa, Hiroaki; Saijo, Hiroyuki

doi:10.1016/0040-6031(85)85202-3

Cited by 26 publications

(8 citation statements)

References 8 publications

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“…It is known that various ZnO nanostructures can be deposited from Zn 2 + -HMT aqueous system since the pioneer work of Vayssieres. 20 However, a few studies have shown that H2O-ethanol component solvent will lead to some special zinc-based compounds including zinc chloride hydroxide, 21 basic zinc carbonate, 6 and zinc fluorohydroxide, 18 which are strongly dependent on the counter ions of Zn 2 + . In our case, where SO 2-4 was used as the counter ions of Zn 2 + , a special zinc based compound zinc sulfate hydroxide hydrate (ZSH) other than ZnO was formed.…”

Section: Resultsmentioning

confidence: 99%

“…The Gibbs free energies for aqueous Zn(NO3)2, Zn(OH)2, and ZnSO4 are -369.6, -461.62, and -891.6 kJ•mol -1 , respectively. 21 As the formation of Zn(OH)2 is the prerequisite for the deposition of ZnO in any aqueous system, the Gibbs energy of the anion with Zn 2 + (i.e., the affinity with Zn 2 + ) will determine the type of precipitates. While ZnO is developed in Zn(NO3)2-HMT H2O-ethanol precursor due to the lower affinity of NO -3 with Zn 2 + than OH -, ZSH is finally formed in ZnSO4-HMT H2O-ethanol system due to the higher affinity of SO [2][3][4] with Zn 2+ than OH -.…”

Section: Resultsmentioning

confidence: 99%

“…2b). 21 Based on the above discussion, the formation mechanism of ZnO transformed from ZSH can be depicted as follows. ZSH in chemical form of 3Zn(OH)2 •ZnSO4 •xH2O first looses the ad-sorbed water and the combined water at 50-200°C, and simultaneously decomposes Zn(OH)2 part to form crystalline ZnO.…”

Section: Resultsmentioning

confidence: 99%

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Porous ZnO Sheets Transformed from Zinc Sulfate Hydroxide Hydrate and Their Photoluminescence Performance

Peng¹,

中国科学院上海硅酸盐研究所

Gao

et al. 2013

Acta Physico-Chimica Sinica

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Highly crystalline, porous ZnO sheets were prepared from chemically-deposited zinc sulfate hydroxide hydrate (ZSH) sheets by sintering at 1000°C. The formation mechanism of ZSH in Zn 2 +hexamethyltetramine (HMT) precursor system, the transformation process of ZSH to ZnO, and the crystalline, microstructural and optical properties of the ZnO sheets were investigated. The porous ZnO sheets possessed a well-defined hexagonal shape with controllable size (10-50 μm) and thickness (200-500 nm), high crystallinity, and strong ultraviolet photoluminescence without detectable defectrelated visible emission. Submicron-sized pores (100-500 nm) and polygonal or irregular ZnO particles resulting from the limited mass transport during high temperature sintering were observed in the ZnO sheets. Analysis of the formation mechanism indicated that the high affinity of SO 2-4 for Zn 2+ was responsible for the formation of ZSH in the Zn 2 + -HMT precursor system, and the thermolysis of ZSH affected the morphology and microstructure of the ZnO sheets. This work reveals a facile route to porous ZnO nanostructures with good crystallinity and optical properties, which make them suitable for application in catalysis, and photo and/or electrical devices.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Porous ZnO Sheets Transformed from Zinc Sulfate Hydroxide Hydrate and Their Photoluminescence Performance

Peng¹,

中国科学院上海硅酸盐研究所

Gao

et al. 2013

Acta Physico-Chimica Sinica

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“…In addition, there is a number of known physical and physicochemical studies [5][6][7][8][9][10][11][12][13][14][15][16][17] which are mainly related to synthetic samples. The most detailed results of calorimetric and magnetic measurements of a synthetic copper sulfate pentahydrate at the temperature of liquid helium and below are given in [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Low-temperature heat capacity and thermodynamic functions of natural chalcanthite

Bissengaliyeva¹,

Bekturganov

Gogol³

et al. 2017

The Journal of Chemical Thermodynamics

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“…Tagawa & Saijo [39] estudaram a cinética da decomposição térmica de alguns sulfatos metálicos em atmosfera de nitrogênio. A análise do mecanismo de decomposição dos foi avaliado através da espessura da camada de produto durante o tempo.…”

Section: Decomposição Térmicaunclassified

Decomposição Térmica Do Sulfato De Zinco Na Presença De Agentes Modificadores Do Mecanismo Reacional

KURBAN¹

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Hydrogen presents itself as a potential alternative fuel to replace fossil fuels and, for this reason, studies and research on the production and storage routes of this resource are in vogue in the scientific community. The methods for obtaining H2 are diverse, however, not all methods are from renewable sources. The thermochemical cycles of splitting water are promising alternatives. In this context, the sulfur-iodine cycle is one of the highlighted cycles, characterized by a threestage process whose third stage is the challenging stage of the cycle, where the decomposition of sulfuric acid occurs, which requires a high energy expenditure for formation selection of sulfur dioxide and oxygen. The use of metal sulfates associated with reducing agents and additives in substitution for sulfuric acid in the sulfur-iodine cycle has been studied. Thus, the present research work evaluated the thermal decomposition of zinc sulfate monohydrate in the presence of elemental sulfur modifying agents, Pd-γAl2O3, CeO2 and CeO2 / ZnO that stimulate the transformation of sulfur trioxide in the respective dioxide. In addition to a thermodynamic study of the reaction system and thermal analyzes via TGA that indicated a change in the sulphate decomposition behavior in the presence of the reducing agent and additives, the work predicted the characterization of the reaction products indicating the presence of zinc oxide and a study kinetics of the systems in the presence of the mentioned agents, allowing the calculation of activation energies and kinetic parameters. The thermodynamic assessment indicated a favorable aspect regarding the decrease in the decomposition temperature of zinc sulfate as well as with regard to the transformation of SO3 into SO2. In the presence of Pd-γAl2O3, the final temperature of the sulphate decomposition occurred 100 ° C below the usual temperature. The total mass loss calculated for the decomposition of pure sulfate was 55%. In studies with the presence of agents, the calculated total mass losses were 60%, 54%, 62%, 57% corresponding to zinc sulfate in the presence of elemental sulfur, Pd-γAl2O3, CeO2 and CeO2 / ZnO, respectively.

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Kinetics of the thermal decomposition of some transition metal sulfates

Cited by 26 publications

References 8 publications

Porous ZnO Sheets Transformed from Zinc Sulfate Hydroxide Hydrate and Their Photoluminescence Performance

Porous ZnO Sheets Transformed from Zinc Sulfate Hydroxide Hydrate and Their Photoluminescence Performance

Low-temperature heat capacity and thermodynamic functions of natural chalcanthite

Decomposição Térmica Do Sulfato De Zinco Na Presença De Agentes Modificadores Do Mecanismo Reacional

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